When using a password protected rpm repository zypper seems to first do a 
GET without credentials, before retrying the GET with credentials:

Here is the first attempt which generates a 401:

 35.237.234.112 - user1 [08/Jun/2020:09:18:28 +0000] "GET /sles/sles-
packages/Module-Public-Cloud/media.1/media HTTP/1.1" 401 204 "-" "ZYpp 17.15.0
(curl 7.60.0) sle-15-x86_64"

Here is the second attempt which succeeds (200).

 35.237.234.112 - user1 [08/Jun/2020:09:18:29 +0000] "GET
/sles/sles-packages/Module-Public-Cloud/media.1/media HTTP/1.1" 200 54 "-"
"ZYpp 17.15.0 (curl 7.60.0) sle-15-x86_64"

This causes failures when using an Artifactory yum repository -- because
Artifactory counts the number of failed logins (401) and will return 403 if
that count gets too high. This leads to package installs failing.